1. Technical Field
The present invention relates to a semiconductor packaging, and more particularly, to a method of manufacturing a semiconductor die having a solder capping without an electrodeposition process.
2. Background
With the recent rapid miniaturization of electronic devices, there is expanding demand for flip-chip technology to satisfy high density interconnections in electronic devices. One popular step in the flip-chip interconnection process involves the deposition of solder alloys onto the bond pads of chips. Among popular bumping technologies, electroplating is one of the more commonly used in industry today. However, there are several problems encountered by the electroplating process at the current technology. General electroplating processes cost more than screen printing or ball dropping processes. In addition, the prohibition of the usage of lead in solder fundamentally alters the composition of the solder. When there are large differences between electrochemical reduction potentials of various constitutions of solder, the electroplating of tin and other metals such as copper is difficult.
Moreover, the control of electrolyte stability is also a universal problem for the electrodeposition of tin and its alloys as in aqueous solutions. The aforementioned factors mean electroplating requires greater operational sophistication and cost.
The current disclosure provides a method of forming a solder capping without using electrodepositing processes. With the introduction of a photoresist layer during the printing or ball dropping process, the current method provides better control of solder paste volume at a lower expenditure than that of an average electrodeposition process.